KENNEDY SPACE CENTER, FLA. - In the Payload Hazardous Servicing Facility, workers prepare to lift the Mars Exploration Rover-1 (MER-B) onto a spin table during preflight processing of the spacecraft. The rover is scheduled to launch aboard a Delta II rocket on June 25. NASA?s twin Mars Exploration Rovers are designed to study the history of water on Mars. These robotic geologists are equipped with a robotic arm, a drilling tool, three spectrometers, and four pairs of cameras that allow them to have a human-like, 3D view of the terrain. Each rover could travel as far as 100 meters in one day to act as Mars scientists' eyes and hands, exploring an environment where humans are not yet able to go. The launch of MER-2 (MER-A) is tentatively set for June 8.